I moonlight as a battery and power systems engineer for EV’s and I can tell you that the most important thing is to not leave the cells sitting at full SOC (state of charge) for more than a few days at a time.
Full SOC 4.2V/cell of the common 18650 cell used in majority of consumer battery packs is very damaging for the long term. But there’s nothing wrong with full charge and using these cells in a short period of time.
As long as you drain some charge from full SOC you’ll reap a significant improvement in longevity and reducing cell degradation.
In practical terms, if you can find 50-60% SOC go right ahead. But merely reducing SOC to between 80-90% from 100% makes much more difference for example than 80% down to 50% SOC.
I’m describing not being used after full charge for more than a few days, week or longer. If you ever full charge and realize you won’t use the Variax, merely “go play your guitar†for 1/2 hour and your pack will love you for it….
jerseyboy's post in Variax Battery Charging was marked as the answer